create an html file with 3d plot

[Long Vo]

Hi all,
This might be a simple issue, but I'm very new to R and `knitr'
I'm trying to follow the example posted by Yihui here,
and created an Rmd file named "rmarkdown1" (also attached)

```{r setup}
library(knitr)
library(rgl)
knit_hooks$set(webgl = hook_webgl)
```

```{r testgl, webgl=TRUE}
x <- sort(rnorm(1000))
y <- rnorm(1000)
z <- rnorm(1000) + atan2(x,y)
plot3d(x, y, z, col=rainbow(1000))
```
Then use the 'Knit HTML' button in Rstudio. The code compiles and created a 3d plot in R console, 
but no HTML file created and an error pops up say:
output file: rmarkdown1.knit.md
Error: path for html_dependency not found

Here is my session info:
R version 3.2.4 (2016-03-10)
Platform: x86_64-w64-mingw32/x64 (64-bit)
Running under: Windows 7 x64 (build 7601) Service Pack 1

locale:
[1] LC_COLLATE=English_Australia.1252  LC_CTYPE=English_Australia.1252   
[3] LC_MONETARY=English_Australia.1252 LC_NUMERIC=C                      
[5] LC_TIME=English_Australia.1252    

attached base packages:
[1] stats     graphics  grDevices utils     datasets  methods   base     

other attached packages:
 [1] shiny_0.14           rmarkdown_1.6        knitr_1.14          
 [4] extrafont_0.17       MASS_7.3-45          rgl_0.98.1          
 [7] plot3D_1.1           scatterplot3d_0.3-40 xlsx_0.5.7          
[10] xlsxjars_0.6.1       rJava_0.9-8          reshape2_1.4.2      
[13] sp_1.2-3            

loaded via a namespace (and not attached):
 [1] Rcpp_0.12.7      plyr_1.8.4       tools_3.2.4      digest_0.6.10   
 [5] jsonlite_1.1     evaluate_0.9     tibble_1.2       gtable_0.2.0    
 [9] lattice_0.20-33  yaml_2.1.13      Rttf2pt1_1.3.4   stringr_1.2.0   
[13] htmlwidgets_0.7  rprojroot_1.2    grid_3.2.4       R6_2.2.2        
[17] ggplot2_2.2.0    extrafontdb_1.0  magrittr_1.5     backports_1.1.0 
[21] scales_0.4.1     htmltools_0.3.5  assertthat_0.1   misc3d_0.8-4    
[25] mime_0.5         colorspace_1.2-6 xtable_1.8-2     httpuv_1.3.3    
[29] stringi_1.1.2    lazyeval_0.2.0   munsell_0.4.3    markdown_0.7.7 

Any suggestions are very much appreciated! 

Long